Inhibition of A2AR gene methylation alleviates white matter lesions in chronic cerebral hypoperfusion rats

Chronic cerebral hypoperfusion (CCH) can cause ischemic cerebral white matter lesions (IWML). The aim of this study was to explore the roles of A2A receptors (A2AR) in IWML and the effect of methylation in A2AR gene.

SD rat model of CCH was constructed by bilateral common carotid artery occlusion (BCCAO) method. The rats were then treated with DNA methyltransferase (DNMT) inhibitor (decitabine), agonist (CGS21680) and A2AR inhibitor (SCH58261). Morris water maze and Kluver-Barrera staining were used to assess spatial learning and reference memory after IWML, respectively. Gene transcription and protein expression were measured by qRT-PCR, Enzyme-linked immunosorbent assay (ELISA) and Western blotting, respectively. The concentration of malondialdehyde (MDA), activity of superoxide dismutase (SOD) and DNMT were detected by assay kit. Methylation of A2AR gene promoter region was detected by bisulfite sequencing PCR (BSP).

We found that the down-regulated expression of A2AR in corpus callosum under CCH was associated with IWML and cognitive impairment. We further showed that A2AR agonist can reduce the IWML under CCH, and A2AR inhibitor can aggravate the IWML under CCH. We also found that the expression level of DNMTs in corpus callosum and the methylation level in the promoter region of A2AR gene were increased under CCH. DNMT inhibitors could protect white matter by inhibiting the methylation of A2AR promoter and rescue the downregulation of A2AR under CCH.

Our results demonstrate that the downregulation of A2AR mediates IWML in CCH, and A2AR downregulation is related to the increased methylation of A2AR gene promoter. DNMT inhibitors play a protective role in IWML.